Lands



May 30, 1933.

w. sIX HAL v 1,911,721

AMPLIFYING INSTALLAT ION Filed Oct. 15, 1950 menial-6': wiZZem Six and;

finip .Z. Tiara/weer pass s May 30,1933

WILLIE SIX AND ANTON LEE-RIDER! TIMKER, OF EINDH OVEN, NETHERLANDS,

ASSIGNOBS TO LANDS N. V. rnmtas GLOEILAHPENFABBIEKEN, OE EINDHOVEN, NETHER- mmme msrsusrron Application filed October 15, 1880,8er1a1 Io. 488,985, and in the Netherlands December 21, 1929.

This invention relates to an amplifying system for use with devices for electrically reproducing sound vibrations.

In the known devices of this type the electrical oscillations produced by the apparatus for translatin the sound vibrations mto electrical oscillations, which may be efiected by means of electric pick-up devices, mlcrophones and the like, are amplified, whereupon these amplified oscillations may be delivered to several groups of loud speakers which are connected, for exam is, in parallel.

The invention relates particularly to an amplifying system in which the said apparatus is connected, preferably throu h the ntermediary of a reliminary 'amphfier, to at least two amplifying units, each of which feeding a group of reproducing units. By the term am 'fying unit is to be understood hereina ter one or more cooperat ng amplifiers feeding a group of reproducing units. This arrangement may beadvantageously used, for example,'with amplifying systems of a paratus for reproducing acoustic films and of installations for use maddressing lar e audiences from a central point b means 0% some groups of loud speakers laced at various points of the space occupied by the audience. With the first mentioned apparatus a plurality of loud speakers is preferably placed in the vicinity of the projection screen, said loudspeakers being connected to a corresponding am lifyin unit. All amplifying units may be ed wit electrical oscillations delivered, for example, by

an electric pick-up device, microphone, radioreceiving apparatus and the like; Such an arran ment has the drawback however, that a who e group of reproducin units is rendered inoperative if one of t e amplifying units breaks down. This constitutes a serious drawback es cially. with apparatus'for reproducin ta ing pictures, since the remaining soun reproduced by the other group of loud speakers, comes only from-one side of of the projection-screen is drawback makes the lprojection screen due to which the effect this manner the said drawback may be avoided, since the intact amplifying unit or units receive the load of the group of reproducing units corresponding to the defective amplifying unit. Of course, the changing over will not fail to-makeits influence felt on the amplifying units to which the additional load is supplied, but by a suitable choice of these units the sound reproduction may be readjusted so as to obtain substantially thesame effect.

It will be obvious that if one of the amplifging units breaks down a group of repro ucing units will be put out of service, though for a short time only. The duration of the period of interruption depends on the time required for tracing the defective unit and for changing over the corresponding group of reproducing units to one or more of the other amplif ing units. Though this interruption perio is of a short duration only, the sound reproduction is unfavourably influencedthereby. This drawback may be avoided by distributing the reproducing 'unitsof each group or of most of the groups about the various amplifying units. If one of the amplifying units breaks down only one or a few units of each group or of most 'of the groups of reproducing units will be rendered'inoperative, while with. talking film apparatus, for example, the effect of the reproduction will substantially be conserved.

The invention will be more clearly understood by reference to the accompanying drawing representing, by way of example,

some embodiments thereof.

- .Fig'. 1 is afschematic diagram of an amdrawing the connection plifying units and the reproducing units will be established through the contacts 16 a which are connecte plifying system showing the principles unerlying the invention.

Fig. 2 is a diagram of an amplifying system according to the invention for use in ap aratus for reproducin acoustic films.

ig. 3 is 'a diagram another form of construction of an amplifying system embodying the invention.

Fig. 1 shows a microphone 1, which is connected to an amplifier 2 by which the electric currents delivered b the microphone are amplified, these ampli ed currents feeding the input circuits of two am lifiers 3 and 4 which are mounted in paralle The amplifiers 3 and 4 are connected to groups of loud speakers 5 and 6 respectively which are placed at various points of the space. Consequently the energy delivered by the microphone is distributed about both groups of loud speakfirs through the intermediary of the ampliers.

Fig. 2 is a dia am of a device for use in reproducing ta ing films in. which 7 is an electric pick-up device which is connected to a defective amp ifying unit may be,

changed over to one or more of the other. amplifying units. As appears from the tween the amand 18 during the normal operation. If, for example, the amplifier breaks down, then one has only to change over to the contact 17, so that the amplifier9 receives the load of the oup of reproducin units 13.

' Fig. 3 shows schematically an amplifyin s stem for use with the so-called public a ess system in which a large audience is addressed from a central point, 19 and 20 and 21 are am lifying units which are jointly .fed from t e apparatus, for example, from a microphone, delivering the electric oscillations which must be transformed into acoustic vibrations by the groups of re roducing units for example, y loud spea ers which are placed at various points of the space occupied by the audience.

The amplifiers 19, 20 and 21 respectively are connected to the loud speaker groups 25 26 and 27 through the intermediary of change-over switches 22, 23 and 24. Each of these groups comprises six 16nd s eakers in parallel in pairs. As appears from the drawin each pair of, loud speakers of each group is connected to the contact establishes the connection between the amplifiers and the corresponding groups of loud s eakersin the-normal working position; f, for example, the amplifier 19 breaks down .two specimens of each group of loud s eakers will be rendered inoperative, so that t e sounddistribution remains substantially the same. Consequently the operator is not hurried in tracing the defectlve amplifier. After the latter has been found the corresponding loud speaker group, viz. the group 19, may be changed over to one of the amphfying units 20 or 21 by changing over rom the contact 19 of the chan e-over switch 22 to the contact 20 or 21, w ereupon this amplifying unit may be readjusted, thus obtaining a re roduction substantially correspondmg to t at obtained formerly. By proceeding 1n this manner the influence of disturbances ma be greatly reduced.

The ampli ers 19, 20, and 21, are connects ed to a common amplifier 8, in turn connected to an electric pick up 7.

What we claim is:

1. An amplifying system for use with apparatus for electrically reproducing acoustlc vibrations, comprising a plurality of amplifier units fed from a common source, a plurality of groups of loud speakers, all ofsubstantiall the same characteristics, each group 0 loud speakers being subdivided into sets of loud speakers, each set of each group of loud speakers being normally fed b a particular amplifier unit separate from t ose by which the remaining sets of each group are fed, and a plurality of switching means interposed, one betweeneach grou of loud speakers and each amplifier unit, or switching, upon break down of one of the amplifier units, the sets of loud speakerscomprising the load thereof among the other amplifier units. I

2. An amplifying system for use with ap paratus for electrically reproducing acoustlc vibrations, comprising a plurality of amplifier units fed from a commonsource, a plurality of groups of loud speakers, all of substantially the same characteristics, each group bein I subdivided into a plurality of sets of Ion -speakers, the corresponding set of each group of loud speakers being connected as the load of a particular amplifier I unit, and switching means interposed, one for eachof the said amplifier units, between said amplifier units and'said groups of loud speakers for distributin upon break down of one of the amplifier units, the load thereof among the other am lifier units.

3. An amp ifying system for electrically reproducing acoustic vibrations in conjunction with a public address system, comprising a plurality of amplifier units fed from a common source. a plurality of groups of loud speakers distributed about the distribution area of the reproduced acoustic vibrations, all the loud speakers having substantially the same characteristics each group being subdivided into a plurality of sets of loud speakers, each set of each group being fed by a different amplifier unit than that which feeds the other sets of that group, and switching means, one for each amplifier unit, for switching, in thejnstance of break down of one of the amplifier units, the sets of loud speakers forming the load thereof among the loads of the other amplifier units.

4. An amplifying system for use with apparatus for electrically reproducing acoustic vibrations, comprising a central amplifier, a plurality of amplifyin units branched from and fed by said centra amplifier, groups of loudspeakers fed from said amplif ing units, all of the loudspeakers having substantially the same characteristics, said groups being placed at various points in space and being electrically divided into sub oups, a subgroup of one group of loudspea ers being connected into the circuit of one amplifying unit together with a subgroup of the other groups of loudspeakers, and switchin means interposed between said groups 0 loudspeakers and said amplifying units for switching, upon breakdown of one of the amplifier units, the loudspeakers forming the load thereof into the load of at least one of the other amplifiers.

In testimony whereof we have signed ,our

names to this specification.

WILLEM SIX.

ANTON LEENDERT TIMMER. 

